I'm trying to enable the external clock source for the ARM Systick timer on the RT1050 EVKB board. The only reference I've found in the manual is in section 10.3.2.1, "Crystal Oscillator (XTALOSC)":
NOTE 24 MHz XTALOSC can be the external clock source of SYSTICK.
From the schematics, the EVKB appears to have a 24 MHz oscillator. If I set the M7 SysTick clock source bit to "Internal", the current value register loads the reload value and starts counting down. However, if I set the M7 SysTick clock source bit to "External", the current value register does not change and does not count.
I've poked around in the XTALOSC registers but I don't see anything that would enable a clock to the M7. Likewise, a search of the reference manual provided no other references to the M7 SysTick and there does not appear to be anything in the clock tree diagrams. How do I enable the M7 SysTick external clock?